I just popped a pimple like lump on my navel, what could it possibly be?

Naval lump. It could be a pimple or it could be some skin infection or a cyst. If it just occurred recently or has been recurrent makes a difference in the diagnosis. If it is recurrent or if it is getting painful and increasingly red, please see your doc.
? painfull. Skin infections can occur any where on the body. Around the navel a hernia can occur. If increasing pain or redness occurs seek help.